NEW ORLEANS — “Field of Dreams” star Kevin Costner has another dream — helping to clean up the massive oil spill that has contaminated the Gulf of Mexico over the past few weeks.

BP has approved a test of Costner’s Ocean Therapy device to help the company clean up the Gulf after its Deepwater Horizon drill rig exploded and began spewing oil into the water, officials said today.

The machine — described as a processing device that separates oil from water — was first developed by scientists hired by Costner following the 1989 Exxon-Valdez oil spill off the coast of Alaska.

“The machines are basically sophisticated centrifuge devices that can handle a huge volume of water and separate at unprecedented rates,” Ocean Therapy Solutions CEO John Houghtaling told CBS’s New Orleans affiliate WWL-TV.

“They were developed from older centrifuge technology. Normal centrifuge machines are very slow and sensitive to different ratios of oil to water mixtures at intake. Costner has been funding a team of scientists for the last 15 years to develop a technology which could be used for massive oil spills.”

The former “Waterworld” actor could not be reached for comment today, but told reporters last week that he wanted to help.

“Years before I got involved, oil spills came and I would wonder why we couldn’t clean this up,” he said.

This comes as tar balls found on beaches in the Florida Keys this week are reportedly not from the Gulf of Mexico oil spill, the U.S. Coast Guard said today, citing laboratory tests.

The news came as a temporary relief to Florida’s tourism authorities, who are already reporting negative market impact from the month-long spillage from BP’s leaking undersea well, the source of a huge slick that has already dumped oil debris ashore on the coasts of Louisiana, Mississippi and Alabama.

The source of the tar balls has not been determined, the Coast Guard said in a statement.

Coast Guard personnel and pollution experts had found around 50 tar balls in recent days in Florida’s Lower Keys, a mecca for divers, snorkelers, fishermen and beach goers. They had sent them to a specialist laboratory to test whether or not they came from the spill.

“The results of those tests conclusively show that the tar balls collected from Florida Keys beaches do not match the type of oil from the Deepwater Horizon oil spill in the Gulf of Mexico.

Nevertheless, the Coast Guard said it remained on the alert for oil contamination.

“The conclusion that these tar balls are not from the Deepwater Horizon oil spill incident in no way diminishes the need to continue to aggressively identify and clean up tar ball-contaminated areas in the Florida Keys,” said Captain Pat DeQuattro, commanding officer of Sector Key West.

Meanwhile, BP said it hopes to begin shooting a mixture known as drilling mud into the blown-out well in the Gulf of Mexico early next week.

Engineers hope to start the procedure known as a “top-kill” by Sunday. It could take several weeks to complete, but if it works it should stop the oil that’s been gushing since the offshore drilling rig Deepwater Horizon exploded off the coast of Louisiana April 20 and sank two days later.

“This is all being done at a depth of 5,000 feet and it’s never been done at these depths before,” said Doug Suttles of BP PLC, the oil giant that was leasing the rig when it exploded.